Command line to find prime factors up to about 20-digit
echo 3103806413962440287812221212283203085698350392832377237909417957870334221892408006347408911746215400810391597189896198939669612838438924060553263406050338934770675270389046808405005098596152777897656677 | ecm -n -c 74 11e3
Command line to find prime factors up to about 25-digit
echo 3103806413962440287812221212283203085698350392832377237909417957870334221892408006347408911746215400810391597189896198939669612838438924060553263406050338934770675270389046808405005098596152777897656677 | ecm -n -c 214 5e4
Command line to find prime factors up to about 30-digit
echo 3103806413962440287812221212283203085698350392832377237909417957870334221892408006347408911746215400810391597189896198939669612838438924060553263406050338934770675270389046808405005098596152777897656677 | ecm -n -c 430 25e4
Command line to find prime factors up to about 35-digit
echo 3103806413962440287812221212283203085698350392832377237909417957870334221892408006347408911746215400810391597189896198939669612838438924060553263406050338934770675270389046808405005098596152777897656677 | ecm -n -c 904 1e6
Command line to find prime factors up to about 40-digit
echo 3103806413962440287812221212283203085698350392832377237909417957870334221892408006347408911746215400810391597189896198939669612838438924060553263406050338934770675270389046808405005098596152777897656677 | ecm -n -c 2350 3e6